In 1982 the de?nition of weakly commuting mappings was given as direct generalization of commuting mappings in the context of metric ?xed point theory. Since then many de?nitions were given for generalizing the previous concept and many papers were published along these thirty years. In order to have an idea of this definition has been invasive in ?xed point theory, it suffices to observe that in Google Scholar the digitization of weakly commuting mappings gives more 20000 voices and related references at February 2012. Many thanks to a few authors which have accepted this invitation to contribute with their manuscript in this volume edited by myself.